Electric protective system



ELECTRC PROTECTIVE SYSTEM Filsd Bday 5l, 1%@

Pnenied Dec. 1s, 1942 UNITED STATES PATENT OFFICE ELECTRIC PROTECTIVE SYSTEM Martin a. neueres, scesi., :v -r., mimmto '-General Electric Company, a corporation' o! New York apumimmy s1, 1940, serial No. 331,982

(ci. ris-ass) achim.

My invention relates to protective systems and more particularly to protective systems for electric valve translating apparatus.

In many applications it is important, in order to meet the load requirements, tooprate apair of electric valve means in parallel relationship.

' For example, the electric valve translating apparatus may comprise a pair of electric valve means connected to operate in parallel by means oi a current-dividing reactor or reactance. In accordance with my invention described hereinafter, I provide a new and improved protective system for arrangements oi this nature.

' It is an object of my invention to provide a new and improved protective system.

It is another object of my invention to provide anew and improved protective or control system for electric valve translating apparatus.

It is a further object oi' my invention to provide a new and improved protective system for electric valve apparatus which includes a pair of electric valve means kconnected to operate in parallel relationship by means of a current-dividing reactor and wherein means are provided to operate in response to the magnetization oi the current-dividingreactor to provide an indication or initiate a circuit controllingor protective operation, when one of the electric valve means fails to conduct current, or conducts current at any time otherthan during predetermined intervals. Y

Briefly stated, in the illustrated embodiment of my invention I provide a new and improved control or protective system for electric valve translating apparatus wherein a pair of electric valve means are connected to operate in parallel relationship, that is, to conduct equal amounts of current concurrently during predetermined intervals oi time. The division of current between the electric valve means is obtained by means of a current-dividing reactor or reactance to equalize the anode-'cathode voltages thereof. I provide means responsive to the magnetization 'of the core member of the reactor to afford an indication or to initiate a circuit controlling operation when one of the electric valves fails to conduct current during the predetermined intervals, or when one of the electric valve means conducts current at any time other than during the l predetermined intervals, or when one of the V electric valves is late in starting to conduct current.

For a better understanding of my invention, reference may be had to the following description, taken inconnection with the accompanying drawing, and its scope-will be pointed out in the appended claims. Fig. 1 of the drawing diagrammatically illustrates an embodiment of my invention as applied to a polyphase rectifier, and Fig. 2 represents a detailed arrangement ci! the relay apparatus responsive: to the magnetization of the current-dividing `reactor. Fig. 3 diagrammatically illustrates a modification of my invention which employsv a'separate or auxiliary control relay.

Referring now to Fig. 1 oi the drawing. I have there diagrammatically illustrated my invention as applied to an electric valve converting system, such as a. rectiiler, for energizing a direct current load circuit i from an alternating current supply circuit 2 through electric translating apparatus comprising a transformer having primary windings 3 and groups of secondary windings 4 and 5. The groups of secondary windings 4 and 5 may be interconnected through an interphase transformer 6 so that the system operates asa double three-phase system. The translating apparatus also includes afplurality o! electric valve means l-ll, inclusive. of the type comprising an ionizable medium, such as a gas or a vapor, and each having an anode I9, a cathode v2i), and may have an associated control member of the immersion ignitor type. The control circuits which, of course, are employed to render the electric valve means 1-i8 conducting are not shown, It will be understood, however, that suitable control circuits for transmitting unidirectional impulses of current to the control members 2l may be used to render the electric valve means conductive in a predetermined order or sequence so that the pairs of electric valves conduct current in parallel relationship. Inasmuch as mercury pool cathodes are employed, it is to be understood that in this particular arrangement the ionizing medium is mercury vapor. Suitable circuit controlling means, such 0i' the intermediate connection 32, provide diilerential current conducting sections each associated with a different one of the electric valve means.

I provide a plurality of relay means 33, each `supported by the core member of the associated current-dividing reactor and which is responsive to the magnetization of the core member. The relays 33 may be arranged to be responsive to the magnetization of the core member occasioned by failure to conduct of one of the associated electricl valve means, or responsive to the magnetization of the core member caused one of the electric valve means conducting current at a time other than during the predetermined intervals. In addition, the relays 33 are responsive to the magnetization oi' the core membersl occasioned by irregular starting of the associated valves as, for example, when one of the electric valves of a pair is initiated in its operation at a time subsequent to the operation of the other.

There is aisoprovided a circuit, such as an indicating circuit, which anords a visual indication upon loss o! control or failure to conduct of onevalve in the respective groups of electric valves. The indicating circuit 34 includes a circuit 33 which is connected to the contacts o! relays 33 and includes a'suitable visual indicating device, such as a glow discharge valve 33 having a minimum potential ionizing characteristic. The glow discharge valve 33 may be connected to a portion of a voltage divider 31 and may be energiaed from a suitable source oi' current, such as a source of alternating current 33, supplied by secondary winding 42 of transformer 33. When the contacts of relays 33 are closed, a voltage is applied to the terminals of the glow discharge valve 33, eifecting ionization thereof and affording a visual indication. l

A suitable relay means 43 is also associated with the indicating circuit 34. The relay means 43 may be provided with an actuating coil 44 and contacts 43 which are normally maintained in the closed circuit position, the actuating coil 44 being normally energized from circuit 33. However, when the contacts of relays 33 close, the actuating coil 44 is shunted thereby permitting vthe relay to open its contacts 43.

able source of current, such as a direct current circuit 43, through current limiting resistance 33. A source of direct current may be provided by a rectifier 3| energized from secondary windings 4I of transformer 33. The relay 41 is arranged so that its contacts 3 2 are normally closed and is arranged to open its contacts 32 with a'denite time delay ii' the fault exists for a predetermined interval of time.

Fig. 2 diagrammatically illustrates a modification of one of the current-dividing reactors, such as current-dividing reactor 23, and the associated relay 33. The current-dividing reactor 23 comprises a core member 33 and the winding 23 is wound around the middle leg of the reactor. The relay 33 comprises .a pair of contacts 34 and 3l which are supported by the core 33 by means of suitable members such as non-magnetic brackets 33 and 31. The movable contact 33 ating coil 43 which'may be energized from a suitmaybemountedonandactuatedbyamagnstie armature 33 whichisattractedtothecemem' vention shown in Fig. 1 will be explained by considering the system when it is operating as a polyphase rectifier to energize the direct current load circuit I. It will be understood that by virtue of the interphase transformer 3, the rectifyins system operates as a double three-phase system and that each pair of electric valves conducts current for substantially electrical degrees, but for only 60 electrical degrees with any one other pair of electric valves. Due to the current-dividing reactors I3I3, the respective pairs of electric valves conduct current in parallel relationship.

The electric valves are rendered conductive in a predetermined order or sequence by excitation circuits (not shown). These excitation circuits supply unidirectional impulses of current to the respective control members Il to eifect the desired sequential operation. Furthermore, the

control members in each group of electric valvesv or each pair of electric valves are cnergiaed simultaneously so that the electric valves conduct current in parallel relationship.

In the event one of the electric valves in an! one of the groups departs from its normal mode of operation, that is, fails to conduct current or loses control by conducting current at any time other than during the predetermined intervals, circuit 34 will substantially coincidentally eifect a visual indication of this irregular operation due to the luminescence of the glow discharge valve 33, and if the fault condition exists for a predetermined number of cycles of the voltage of circuit 3, circuit 43 will be controlled to mord an indication of the continued irregular operation. Circuit 43 may be used to initiate a circuit controlling or protective operation in response to the' continued loss of control or failure to conduct.

Referring more particularly to the operation of circuit 34 in the event one of the electric valves in a particulargroup loses control or fails to conduct during the desired intervals, the contacts 34 and 33 of the associated relay will be closed, shunting the .actuating coil 44 of relay 43. concurrently with this operation, closure of the contacts 34 and 33 completes the circuit for the energization of the glow discharge valve 43, affording an immediate visual indication of irregular operation. When the contacts 43 of relay 43 open, the actuating coil 43 of relay 41 is energized and the contacts 33 of relay 41 are opened witha time delay. If the fault exists for the pre-established interval of time, contacts 32' are opened. It is to be understood that if one of the electric valves fails to conduct current during predetermined intcrvals or loses control by conducting current at any time other than during the intervals, or if the pairs of valves do not become conductive at precisely the same instant. there aaoasao will be established in the core members 53 of the current-dividing reactors 23-28 magnetic fluxes due to the differential effect of windings 29. Consequently, the relays 33 will be actuated and the contacts 54 thereof Will be closed to initiate the above-described sequence of operation.

In Fig. 3 a modification of my invention is shown which is similar generally to the arrangement of Fig. l and corresponding elements have been assigned like reference numerals. A separate or auxiliary relay 59 is employed which ls similar in many respects to the relay structure shown in Fig. 2. The relay 59 comprises a core member 6U having a pair of opposing winding sections or windings 6i and 62 and having contacts 63 and 6I which are mounted on an armature member 65 which, in turn, is responsive to the magnetization of the core member 60. Winding 6i is connected in series relation with electric valve 1, and winding 62 is connected in series relation with electric valve 8.

If the electric valves conduct current in parallel relationship, that is, conduct during the same intervals of time and initiate the periods of conduction at the same instant, there will be no magnetization of the core member 80 and hence the armature 65 will not be actuated. However, ii' the electric valves l and 8 fail to conduct current during the same intervals oi' time, or lose control by conducting current during intervals other than the predetermined intervals oi' time, or fail to initiate the intervals of conduction at the same instant, the armature 85 will be actuated due to the magnetization of the core 50, closing contacts 83 and BI and thereby controlling circuit 35.

While I have shown and described my invention as applied to a particular system o! connections and as embodying various devices diagrammatically shown, it will be obvious to those skilled in the art that changes and modications may be made without departing from my invention, and I, therefore, aim in the appended claims to cover all such changes and modincations as i'all within the true spirit and scope oi' my invention.

What I claim as new and desire to secure by Letters Patent of the United States is: g

1'. In combination, an alternating currentv circuit, a direct current circuitl electric-translating apparatus connected between said circuits and comprising a pair oi' electric valves. means for dividing the current between said electric valves so that said electric valves conduct current in parallel relationship and comprising a magnetic core member having a winding associated therewith having differentially opposed sections thereof each associated with a different one of said electric valves. a control circuit, means responsive to a magnetic condition oi' said core member to control the energization of said control circuit when one oi' said electric valves fails to conduct current, a second control circuit, and means for controlling the energization of said second control circuit when said one electric valve fails to conduct current for a predetermined number oi' cycles of said alternating current circuit.

2. In combination, an alternating current circuit, a direct current circuit, electric translating apparat-us connected between said circuits and comprising a pair of electric valves, means for dividing the current between said electric valves so that electric valves conduct current in par-` allel relationship and comprising a magnetic core member having a winding associated therewith having differentially opposed sections thereof each associated with a dill'erent one oi said elecv tric valves, a control circuit, means responsive to the magnetization oi' said core member to energize said control circuit when one of said electric valves fails to conduct current, a second control circuit, and means for energizing said second control circuit when said one electric valve fails to conduct current for a predetermined number oi cycles oi said alternating current circuit.

3. In combination, an alternating current circuit, a direct current circuit, electric translating apparatus connected between said circuits and comprising a pair of electric valve means arranged to conduct current in parallel relationship, a control circuit, and means for controlling said control circuit in response to the current conducted by the electric valve means comprising an inductive device having a core member,

a winding associated with said core member having a pairof differential sections each responsive to the current conducted by a different one of said electric'valve means and armature means mounted on said core member and comprising a magnetic portion directly responsive to the magnetization of said core member.

4. In combination, an alternating current circuit, a direct current circuit, electric translating apparatus connected between said circuits and comprising a pair of electric valve means and an inductive device for controlling said electric valve means so that said electric valve means conducts current in parallel relationship, a control circuit, and means for controlling said control circuit in response to the current conducted by said electric valve means comprising a magnetic relay having a core member, a winding associated with said core member having a pair of differential sections each responsive to the current conducted by a different one of said electric valve means, a pairof contacts and armature means mounted on said core member and comprising a magnetic portion directly responsive to the magnetization oi said core member for actuating said contacts.

MARTIN A EDWARDS. 

